If after the great financial crisis of 2007-2009 the word “extraordinary” characterised monetary policy, the Covid-19 pandemic calls for a much stronger adjective: “unprecedented”.
As the world has never before been faced with an instance when virtually all economic activity stopped for a certain period of time, this is an appropriate word. However, in monetary policy really very little can be said to be truly “unprecedented”.
For example, take modern monetary theory (MMT) — a theory about how to have your (monetary) cake and eat it, which (simplistically) states that if a country can print its own currency, that country will never default on its debt because it can create as much currency as it wants to and use it to pay back the debt.
Major central banks, to a certain degree, have already begun versions of MMT.